32a9a245d7
In the bdrv_snapshot_goto() fallback code, we work with a pointer to either bs->file or bs->backing. We detach that child, close the node (with .bdrv_close()), apply the snapshot on the child node, and then re-open the node (with .bdrv_open()). In order for .bdrv_open() to attach the same child node that we had before, we pass "file={child-node}" or "backing={child-node}" to it. Therefore, when .bdrv_open() has returned success, we can assume that bs->file or bs->backing (respectively) points to our original child again. This is verified by an assertion. All of this is not immediately clear from a quick glance at the code, so add a comment to the assertion what it is for, and why it is valid. It certainly confused Coverity. Reported-by: Coverity (CID 1452774) Signed-off-by: Max Reitz <mreitz@redhat.com> Message-Id: <20210503095418.31521-1-mreitz@redhat.com> [mreitz: s/close/detach/] Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>